suspected tablet memory leak

here is the memory total info:

------------------------------------------------
MALLOC: 1691715680 ( 1613.3 MiB) Bytes in use by application
MALLOC: + 178733056 ( 170.5 MiB) Bytes in page heap freelist
MALLOC: + 37483104 ( 35.7 MiB) Bytes in central cache freelist
MALLOC: + 4071488 ( 3.9 MiB) Bytes in transfer cache freelist
MALLOC: + 13739264 ( 13.1 MiB) Bytes in thread cache freelists
MALLOC: + 12202144 ( 11.6 MiB) Bytes in malloc metadata
MALLOC: ------------
MALLOC: = 1937944736 ( 1848.2 MiB) Actual memory used (physical + swap)
MALLOC: + 311296 ( 0.3 MiB) Bytes released to OS (aka unmapped)
MALLOC: ------------
MALLOC: = 1938256032 ( 1848.5 MiB) Virtual address space used
MALLOC:
MALLOC: 174694 Spans in use
MALLOC: 201 Thread heaps in use
MALLOC: 8192 Tcmalloc page size
------------------------------------------------
Call ReleaseFreeMemory() to release freelist memory to the OS (via madvise()).
Bytes released to the OS take up virtual address space but no physical memory.

but in memroy detail, sum of all the sub Current Consumption is far less than the to the root Current Consumption。